the world series. mitt romney, behind in all battleground polls for the last three weeks, now has the most to gain from a game-changing night. and the most to lose if he doesn't turn it around. as the candidates head to debate camp, rolling up their sleeves, getting down to work, each claims to be the underdog. >> governor romney, he's -- he's a good debater. i'm just okay. >> he plays, barack obama, he plays them well, too. i hate to tell you. >> reporter: mitt romney practicing with ohio senator rob portman looks like he's been getting a workout. the president sparring with john kerry, even chose a key suburb in nevada, a battleground state, for his practice session. neither candidate is known as a great debater. aides say the president doesn't like to talk in sound bites, and can be patronizing. >> you're likeable enough, hillary. >> thank you. >> reporter: romney, say advisers, can come off as out of touch with average voters. >> rick, i'll tell you what, 10,000 bucks? $10,000 bet? >> reporter: in the 52 years since the debates were first televised the first rule is appearances count.